From 4d33de9b4975be0f3450fa44d6c912e4331ca0c8 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Tue, 25 May 2021 21:56:25 +0200 Subject: [PATCH] rlp: optimize big.Int decoding for size <= 32 bytes (#22927) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This change grows the static integer buffer in Stream to 32 bytes, making it possible to decode 256bit integers without allocating a temporary buffer. In the recent commit 088da24, Stream struct size decreased from 120 bytes down to 88 bytes. This commit grows the struct to 112 bytes again, but the size change will not degrade performance because Stream instances are internally cached in sync.Pool. name old time/op new time/op delta DecodeBigInts-8 12.2µs ± 0% 8.6µs ± 4% -29.58% (p=0.000 n=9+10) name old speed new speed delta DecodeBigInts-8 230MB/s ± 0% 326MB/s ± 4% +42.04% (p=0.000 n=9+10) --- rlp/decode.go | 60 ++++++++++++++++++++++++++++++++++++---------- rlp/decode_test.go | 22 ++++++++++++++--- rlp/encode_test.go | 8 +++++++ 3 files changed, 74 insertions(+), 16 deletions(-) diff --git a/rlp/decode.go b/rlp/decode.go index 8121ab2e72..ac04d5d569 100644 --- a/rlp/decode.go +++ b/rlp/decode.go @@ -220,20 +220,51 @@ func decodeBigIntNoPtr(s *Stream, val reflect.Value) error { } func decodeBigInt(s *Stream, val reflect.Value) error { - b, err := s.Bytes() - if err != nil { + var buffer []byte + kind, size, err := s.Kind() + switch { + case err != nil: return wrapStreamError(err, val.Type()) + case kind == List: + return wrapStreamError(ErrExpectedString, val.Type()) + case kind == Byte: + buffer = s.uintbuf[:1] + buffer[0] = s.byteval + s.kind = -1 // re-arm Kind + case size == 0: + // Avoid zero-length read. + s.kind = -1 + case size <= uint64(len(s.uintbuf)): + // For integers smaller than s.uintbuf, allocating a buffer + // can be avoided. + buffer = s.uintbuf[:size] + if err := s.readFull(buffer); err != nil { + return wrapStreamError(err, val.Type()) + } + // Reject inputs where single byte encoding should have been used. + if size == 1 && buffer[0] < 128 { + return wrapStreamError(ErrCanonSize, val.Type()) + } + default: + // For large integers, a temporary buffer is needed. + buffer = make([]byte, size) + if err := s.readFull(buffer); err != nil { + return wrapStreamError(err, val.Type()) + } + } + + // Reject leading zero bytes. + if len(buffer) > 0 && buffer[0] == 0 { + return wrapStreamError(ErrCanonInt, val.Type()) } + + // Set the integer bytes. i := val.Interface().(*big.Int) if i == nil { i = new(big.Int) val.Set(reflect.ValueOf(i)) } - // Reject leading zero bytes. - if len(b) > 0 && b[0] == 0 { - return wrapStreamError(ErrCanonInt, val.Type()) - } - i.SetBytes(b) + i.SetBytes(buffer) return nil } @@ -563,7 +594,7 @@ type Stream struct { size uint64 // size of value ahead kinderr error // error from last readKind stack []uint64 // list sizes - uintbuf [8]byte // auxiliary buffer for integer decoding + uintbuf [32]byte // auxiliary buffer for integer decoding kind Kind // kind of value ahead byteval byte // value of single byte in type tag limited bool // true if input limit is in effect @@ -817,7 +848,7 @@ func (s *Stream) Reset(r io.Reader, inputLimit uint64) { s.kind = -1 s.kinderr = nil s.byteval = 0 - s.uintbuf = [8]byte{} + s.uintbuf = [32]byte{} } // Kind returns the kind and size of the next value in the @@ -927,17 +958,20 @@ func (s *Stream) readUint(size byte) (uint64, error) { b, err := s.readByte() return uint64(b), err default: + buffer := s.uintbuf[:8] + for i := range buffer { + buffer[i] = 0 + } start := int(8 - size) - s.uintbuf = [8]byte{} - if err := s.readFull(s.uintbuf[start:]); err != nil { + if err := s.readFull(buffer[start:]); err != nil { return 0, err } - if s.uintbuf[start] == 0 { + if buffer[start] == 0 { // Note: readUint is also used to decode integer values. // The error needs to be adjusted to become ErrCanonInt in this case. return 0, ErrCanonSize } - return binary.BigEndian.Uint64(s.uintbuf[:]), nil + return binary.BigEndian.Uint64(buffer[:]), nil } } diff --git a/rlp/decode_test.go b/rlp/decode_test.go index 36d254e18e..7c3dafeac4 100644 --- a/rlp/decode_test.go +++ b/rlp/decode_test.go @@ -329,6 +329,11 @@ type recstruct struct { Child *recstruct `rlp:"nil"` } +type bigIntStruct struct { + I *big.Int + B string +} + type invalidNilTag struct { X []byte `rlp:"nil"` } @@ -405,10 +410,11 @@ type ignoredField struct { } var ( - veryBigInt = big.NewInt(0).Add( + veryBigInt = new(big.Int).Add( big.NewInt(0).Lsh(big.NewInt(0xFFFFFFFFFFFFFF), 16), big.NewInt(0xFFFF), ) + veryVeryBigInt = new(big.Int).Exp(veryBigInt, big.NewInt(8), nil) ) var decodeTests = []decodeTest{ @@ -479,12 +485,15 @@ var decodeTests = []decodeTest{ {input: "C0", ptr: new(string), error: "rlp: expected input string or byte for string"}, // big ints + {input: "80", ptr: new(*big.Int), value: big.NewInt(0)}, {input: "01", ptr: new(*big.Int), value: big.NewInt(1)}, {input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt}, + {input: "B848FFFFFFFFFFFFFFFFF800000000000000001BFFFFFFFFFFFFFFFFC8000000000000000045FFFFFFFFFFFFFFFFC800000000000000001BFFFFFFFFFFFFFFFFF8000000000000000001", ptr: new(*big.Int), value: veryVeryBigInt}, {input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works {input: "C0", ptr: new(*big.Int), error: "rlp: expected input string or byte for *big.Int"}, - {input: "820001", ptr: new(big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"}, - {input: "8105", ptr: new(big.Int), error: "rlp: non-canonical size information for *big.Int"}, + {input: "00", ptr: new(*big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"}, + {input: "820001", ptr: new(*big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"}, + {input: "8105", ptr: new(*big.Int), error: "rlp: non-canonical size information for *big.Int"}, // structs { @@ -497,6 +506,13 @@ var decodeTests = []decodeTest{ ptr: new(recstruct), value: recstruct{1, &recstruct{2, &recstruct{3, nil}}}, }, + { + // This checks that empty big.Int works correctly in struct context. It's easy to + // miss the update of s.kind for this case, so it needs its own test. + input: "C58083343434", + ptr: new(bigIntStruct), + value: bigIntStruct{new(big.Int), "444"}, + }, // struct errors { diff --git a/rlp/encode_test.go b/rlp/encode_test.go index 08a2a84c62..25d4aac267 100644 --- a/rlp/encode_test.go +++ b/rlp/encode_test.go @@ -131,6 +131,14 @@ var encTests = []encTest{ val: big.NewInt(0).SetBytes(unhex("010000000000000000000000000000000000000000000000000000000000000000")), output: "A1010000000000000000000000000000000000000000000000000000000000000000", }, + { + val: veryBigInt, + output: "89FFFFFFFFFFFFFFFFFF", + }, + { + val: veryVeryBigInt, + output: "B848FFFFFFFFFFFFFFFFF800000000000000001BFFFFFFFFFFFFFFFFC8000000000000000045FFFFFFFFFFFFFFFFC800000000000000001BFFFFFFFFFFFFFFFFF8000000000000000001", + }, // non-pointer big.Int {val: *big.NewInt(0), output: "80"},